In a moment when the construction sector is working hard to deliver a more sustainable built environment, could the solution be found in one of the oldest building materials, arguably, the original sustainable material?
With all the various low-carbon built environment drivers and targets, the time is ripe for less the invention of a new product, but more the reinvention of an age old low-carbon material – natural stone.

While stone has been the building material of choice for those constructing our towns and cities for thousands of years, in recent years the perception of natural stone has shifted it from being seen as a mainstream construction product to simply a high-end finishing material, after millennia of time-proven approaches to building with stone, some would argue that we’ve had almost a century of forgetting, but this is changing.

There is a fresh excitement and optimism within the stone sector as the objective, statistical embodied and whole life carbon savings of using natural stone are cutting through the noise of the greenwashing of some of the other, less sustainable material choices.

It would be impossible to talk about the renaissance that stone is experiencing without referencing the excitement around the carbon savings possible with structural stone or load-bearing stone projects.
While the engineering approaches being utilised are most definitely innovative and modern, the basic concept is something decidedly traditional. You only need look at any of the UK’s cathedrals, stately homes or historic university buildings to see that utilising both the beauty but also the strength and durability of natural stone is a time-proven principle.
From a structural engineer’s perspective, stone is an ideal material choice, delivering both low carbon but also high strength. Steve Webb, Director at Webb Yates Engineers, wrote recently,
“Stone is very low carbon compared to other materials, while mostly stones are more than double the strength and long-term stiffness of a standard concrete mix. With an average carbon content of 0.06kg/kg, however, it has about 1/3 of the carbon footprint of concrete.”

One project that demonstrates a number of these principals is London-based architect, Amin Taha’s 15 Clerkenwell Close project. Completed in 2017 and situated in the heart of Islington, this headline making project has gone on to win a Royal Institute of British Architects National Award and be shortlisted for the internationally renowned Stirling Prize.

Not only is the building’s aesthetic striking but, the statistics behind the structure are what have made it such a headline hitting project. By choosing stone, Amin Taha has reduced the embodied carbon of the structure by 90% and lowered the financial cost by 75% compared to typical steel and concrete frames. 

This ability to use natural stone to reduce both the carbon and financial costs of construction has, rightly so, caused quite a stir within the UK architectural community.

The statistics around this project don’t stand in isolation, there are a growing number of studies and university research papers that are showcasing the case for stone. To name but a few:

– A recently published and verified UK Limestone EPD had an embodied carbon figure of 44.7 kg/CO2 pr tonne of material. Put this alongside the result of a pre-cast concrete EPD which came out with a figure of 242 and we see how the simple shift of material from pre-cast concrete to natural stone can make an embodied carbon saving of 137%.
– A study by Swiss research body, MDPI found that the shift from concrete to structural stone construction could save the construction industry up to 75% on its carbon output.
– MAKE Architects undertook research that found to compare the embodied carbon different façade systems. In their study they found that natural stone, and in this case specifically Portland Stone from Albion Stone had the lowest carbon of the various façade products in their study. In Stages A1 – A3 the 50mm limestone façade had a value of 15.5kgco2 in comparison to brick at 40.5, precast concrete with 86 and ceramic tiles at 90.

The story around stone’s sustainability credentials is on the rise and gaining significant recognition. 

This month it was announced that a project focussing on the part that UK stone can have in decarbonising the built environment was chosen as the winner of the RIBA Scott Brownrigg Award for Sustainable Development.
Launched in 2022, RIBA’s Scott Brownrigg Award for Sustainable Development offers £10,000 to individuals or teams interested in developing research projects or practical work in architecture-related topics associated with one or more of the 17 Sustainable Development Goals of the United Nations Global Compact. 

This recognition and investment by RIBA will sit alongside a number of other public bodies, universities and Government funds including Historic Environment Scotland who are working to bring Scottish Granite back to the market, Bath University who have commissioned a structural stone PHD and the Government’s Future Observatory Fund that is looking to support a structural stone code, that are all seeking to help make stone and specifically UK stone a significant part of the main stream construction sector just as it once was.

In 1959, Scottish architect James Shearer wrote in the RIAS Quarterly, “It is widely believed that in Scotland we cannot afford to use stone. Stone is not used because it is too dear, and it is too dear because it is not used.”
This ‘chicken and egg’ challenge that the Scottish stone industry found itself in 66 years ago is, in many ways the same challenge that the UK stone industry as a whole find itself in today.

But all is not lost.

Within the context of a built environment that is working hard to decarbonise itself an ever-increasing number of architects, designers, structural engineers and clients are discovering that the solution might just be found in arguably the original sustainable material: natural stone.